Catheter-days versus patient-days

The NPSA Matching Michigan project team have recently reviewed wether catheter-days or patient-days are collected during central line surveillance. We are pleased to confirm that the project team are going to include catheter-days as one of the denominators. The team state “At the Manchester meeting for the NPSA Matching Michigan project, we said we would only collect one denominator for calculating CVC-BSI rates: CVC-patient days. The reason for this was that a few centres had inadvertently transposed data when collecting two denominators (CVC-days as well as CVC-patient days).

After our meeting in Manchester, several of you told us that you were already collecting CVC-days (that is, the total number of CVCs, not just the number of patients with one or more CVCs). We are also aware that there is considerable diversity (or lack of clarity) in the literature about denominator measures. Therefore, after reflection and discussion, we propose to revert to our original plan, to ask you to collect both denominators. We apologise for this change but given current diversity of practice, we think it is important to offer both metrics, we hope you agree. We believe that this will be the first such study to use both measures explicitly.”